Rear brake Lock-up 70 C30 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CCCC · 02-01-2017, 05:37 PM

Went out this AM to move the tow truck from the storage garage for some carb work and found that one rear wheel is almost locked (dually). The truck will move backward with some strain but will not push forward. Low fluid level in the rear bowl on the master cyl tells me there must be a leak and it's probably at that wheel - although no exterior evidence.

Would such a leak cause the brake shoes to swell enough to lock up on the drum?

Numerous "pumps" of the pedal after filling the MC does not seem to have helped break it loose and, in that the other rear wheel spins OK, it seems like this is not a rear hydraulic lock-up. While I'm preparing to drag the truck into a workspace and tear into it, have you encountered such a surprise? And, what was wrong?

02-01-2017, 05:37 PM	#1
CCCC Registered User Join Date: Mar 2007 Location: San Pedro River, SE Arizona Posts: 734	Rear brake Lock-up 70 C30 Went out this AM to move the tow truck from the storage garage for some carb work and found that one rear wheel is almost locked (dually). The truck will move backward with some strain but will not push forward. Low fluid level in the rear bowl on the master cyl tells me there must be a leak and it's probably at that wheel - although no exterior evidence. Would such a leak cause the brake shoes to swell enough to lock up on the drum? Numerous "pumps" of the pedal after filling the MC does not seem to have helped break it loose and, in that the other rear wheel spins OK, it seems like this is not a rear hydraulic lock-up. While I'm preparing to drag the truck into a workspace and tear into it, have you encountered such a surprise? And, what was wrong? __________________ CCCC 67 Sting Ray Coupe 327 4sp; 68 K10 Suburban 327 4sp; 69 K20 Lifted 383 4sp; 69 C80 Fire Truck 478 V6 5sp/2sp; 69 C20 Longhorn 327 4sp; 70 C30 Wrecker 350 4sp; 70 C30 Flat Bed 350 4sp; 71 C20 LWB 350 4sp; 72 K5 Blazer 350 4sp; 72 C30 Flat Bed Gooseneck Hauler with sleeper 350/TH400; 72 C20 Longhorn 402 4sp; 52 Mack LTL Supercharged Cummins 5sp x 3sp; 01 Dodge 5.9 HO Cummins 6spd; 02 Safari Trek 2430 8.1 Vortec on Workhorse Chassis; 03 Silverado 2500 HD 4wd Duramax/Allison Moved but still in the family 70 C20 Custom Camper 350/TH350; 72 K5 Blazer CST Highlander 350/TH350 Recently sent to new homes 72 C30 MoHome 402 4sp; 72 K5 Blazer Conv 350 4sp; 75 GMC 6000 Aerial 350 w Allison; 72 GMC 3500 Utility 350 4sp; 70 GMC 3500, 350 4sp



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